Conventional door locks operate according to mechanical locking mechanisms using keys and locks. Recently supplied digital door locks are electronically controlled via an electronic circuit included in door locks. In particular, the digital door locks are mostly used for doors of hotel rooms.
Door locks used in hotels may be released by using magnetic cards. Hotel managers may record information on the magnetic cards to be provided to customers, by using magnetic card writers. The information recorded on the magnetic cards may include room numbers and lengths of stay of the customers in the rooms.
The customers may insert the magnetic cards into the door locks of the rooms. The door locks may read the recorded information from the magnetic cards. The door locks may compare the read information with information set in the door locks. The information set in the door locks may include the room numbers corresponding to the door locks and a current time.
The door locks may determine whether the room numbers included in the read information and the room numbers included in the information set in the door locks match each other. The door locks may determine whether the current time is within the lengths of stay included in the read information. The door locks may be unlocked based on results of the determination.
However, since the magnetic cards are easily duplicated, such door locks may have weak security. Also, such door locks generally do not have remote communication functions. Accordingly, it may be difficult for servers to separately manage histories of locking/unlocking the door locks.
Recently, door locks having remote communication functions have been introduced, but are not widely used due to problems of cost. Accordingly, the door locks that are unlocked by using the magnetic cards are still widely used.
Also, with the development of communication technology and miniaturization of electronic devices, personal terminals are widely used by general consumers. In particular, recently, personal portable terminals, such as smart phones or smart tablet personal computers (PCs), have become widespread. The smart phones include communication modules, and applications using the communication modules are being developed.